1. Field
Example embodiments relate to a transmitting device and receiving device for selecting a transmit channel in a wideband high frequency wireless system using a plurality of transmit antenna, and a method thereof.
2. Description of the Related Art
A wideband high frequency wireless system uses a high frequency such as a millimeter wave having a strong straightness, and thus, poor communication may occur due to an obstacle, and serious degradation in a communication quality may occur depending on a degradation in a channel status in a wireless channel environment.
Accordingly, multiple antennas that may provide multiple communication paths and an adaptive modulation and coding scheme (MCS) are used in a recent communication system.
However, to transmit a signal via a plurality of antennas at the same time, the same number of radio frequency (RF) chains as a number of the plurality of antennas are used, thereby causing complex hardware, a high electronic power, and a high cost. Accordingly, since the described configuration is not suitable for a system requiring a low cost and a low electronic power, a system including a plurality of antennas and a signal RF chain to enable a single antenna to be used at a specified time, is required.
That is, when a channel status is good, a relatively higher transmission rate is provided by using a high modulation in which a number of transmission bits per symbol is high and by reducing an amount of additional bit information used for channel coding. When the channel status is poor, a quality of signal transmission is maintained even though a relatively lower transmission rate is provided by using a low modulation in which the number of transmission bits per symbol is low and by increasing the amount of additional bit information used for the channel coding.
As described above, a device including the plurality of antennas and the single RF chain may require a method of selecting a single antenna which may provide an optimal transmit channel.
In a conventional art, an antenna which provides the best signal transmission quality is selected by exchanging a control call between a transmitting device and a receiving device prior to data communication between transmitting/receiving devices, and communication is performed via the selected antenna.
The receiving device compares a quality of a received signal with a predetermined standard value during the data communication, and transmits, to the transmitting device, measured channel status information together with a request for changing the antenna when the quality of the received signal is less than the predetermined standard value.
The transmitting device applies a proper MCS to current channel status information after being informed of the request for changing the antenna together with the channel status information of the current channel by the receiving device. Also, when communication over a certain quality level may not be supported with any MCS parameter due to excessive degradation of the channel status, the current antenna is no longer used and another antenna is selected to be used.
However, the method of selecting a transmit antenna disclosed in the conventional art may select another antenna only after poor communication occurs in the currently used antenna, and a desired quality for a signal may not be guaranteed via the selected antenna.